Lab-scale experiment of a closed thermochemical heat storage system including honeycomb heat exchanger Armand Fopah-Lele a, b, * , Christian Rohde a , Karsten Neumann a , Theo Tietjen a , Thomas R € onnebeck a , Kokouvi Edem N'Tsoukpoe c , Thomas Osterland d , Oliver Opel a , Wolfgang K.L. Ruck a a Sustainable Energy Research and Environmental Chemistry Institute, Faculty of Sustainability Sciences, Leuphana University Lüneburg, Scharnhorststraße 1, Geb. 16, 21335, Lüneburg, Germany b Univ Lyon, CNRS, INSA-Lyon, Universit e Claude Bernard Lyon 1, Center for Energetic and Thermal Sciences of Lyon (CETHIL) UMR5008, F-69621, Villeurbanne, France c Laboratoire Energie Solaire et Economie d'Energie (LESEE), D epartement G enie Electrique, Energ etique et Industriel, Institut International d'Ing enierie de l'Eau et de l'Environnement, 01 BP 594, Ouagadougou 01, Burkina Faso d Faculty of Mechanical and Process Engineering, University of Applied Sciences, An der Hochschule 1, 86161, Augsburg, Germany article info Article history: Received 27 October 2015 Received in revised form 21 July 2016 Accepted 3 August 2016 Keywords: Thermochemical storage Honeycomb heat exchanger Thermal performance Cycling tests Space heating Salt hydrates abstract A lab-scale thermochemical heat storage reactor was developed in the European project “thermal bat- tery” to obtain information on the characteristics of a closed heat storage system, based on thermo- chemical reactions. The present type of storage is capable of re-using waste heat from cogeneration system to produce useful heat for space heating. The storage material used was SrBr 2 $6H 2 O. Due to agglomeration or gel-like problems, a structural element was introduced to enhance vapour and heat transfer. Honeycomb heat exchanger was designed and tested. 13 dehydration-hydration cycles were studied under low-temperature conditions (material temperatures < 100  C) for storage. Discharging was realized at water vapour pressure of about 42 mbar. Temperature evolution inside the reactor at different times and positions, chemical conversion, thermal power and overall efficiency were analysed for the selected cycles. Experimental system thermal capacity and efficiency of 65 kWh and 0.77 are respectively obtained with about 1 kg of SrBr 2 $6H 2 O. Heat transfer fluid recovers heat at a short span of about 43  C with an average of 22  C during about 4 h, acceptable temperature for the human comfort (20  C on day and 16  C at night). System performances were obtained for a salt bed energy density of 213 kWh$m 3 . The overall heat transfer coefficient of the honeycomb heat exchanger has an average value of 147 W m 2 K 1 . Though promising results have been obtained, ameliorations need to be made, in order to make the closed thermochemical heat storage system competitive for space heating. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction The addition of energy storage units to thermal energy systems for residential heating and cooling was proposed decades ago [1]. At that time, researchers believed that combining energy storage and existing systems (heat pumps for example) was economically not realistic. However, Katulic et al. [2] recently proved that, thermal energy can also be accumulated while electricity market prices remain low and discharged whereas prices remain high via a conversion chain-like electricity-heat-chemical-heat-electricity. Therefore, thermochemical heat accumulation appears promising, though not yet commercialized. In a similar approach, while considering combined heat and power (CHP) or cogeneration plant and hot water tank for district heating, Bogdan et al. [3] noted both the economic and environmental benefits of using thermal energy storage system within a CHP plant. Streckien _ e et al. [4] studied the feasibility of a coupled CHP with a thermal energy storage system in the German energy market. From their work, they draw the conclusion that combining thermal energy storage (TES) with a CHP could reduce the CHP-plant investment and reduce the simple * Corresponding author. Univ Lyon, CNRS, INSA-Lyon, Universit e Claude Bernard Lyon 1, Center for Energetic and Thermal Sciences of Lyon (CETHIL) UMR5008, F- 69621, Villeurbanne, France E-mail addresses: armand.fopah-lele@insa-lyon.fr (A. Fopah-Lele), ruck@ leuphana.de (W.K.L. Ruck). Contents lists available at ScienceDirect Energy journal homepage: www.elsevier.com/locate/energy http://dx.doi.org/10.1016/j.energy.2016.08.009 0360-5442/© 2016 Elsevier Ltd. All rights reserved. Energy 114 (2016) 225e238